<!DOCTYPE html>
<html lang="zh-cn">
<head>
    <meta charset="UTF-8">
    <title>SockJS</title>

</head>
<body>

<input id="text" type="text" title="发送的文本"/>
<button onclick="send()">Send</button>
<button onclick="closeWebSocket()"> Close</button>
<div id="message"></div>

<script src="https://cdn.jsdelivr.net/npm/sockjs-client@1/dist/sockjs.min.js"></script>
<script type="text/javascript">

    var websocket = new SockJS('http://localhost:8080/ws/hello');
    //连接发生错误的回调方法
    websocket.onerror = function () {
        setMessageInnerHTML("error");
    };

    //连接成功建立的回调方法
    websocket.onopen = function (event) {
        setMessageInnerHTML("open");
    };

    //接收到消息的回调方法
    websocket.onmessage = function (event) {
        setMessageInnerHTML(event.data);
    };

    //连接关闭的回调方法
    websocket.onclose = function () {
        setMessageInnerHTML("close");
    };

    //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
    window.onbeforeunload = function () {
        websocket.close();
    };

    //将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
        document.getElementById('message').innerHTML += innerHTML + '<br/>';
    }

    //关闭连接
    function closeWebSocket() {
        websocket.close();
    }

    //发送消息
    function send() {
        var message = document.getElementById('text').value;
        websocket.send(message);
    }
</script>

</body>
</html>